In domestic low-voltage wiring, one form of wiring is a double-core flat cable insulated with vinyl insulation (referred to as VVF cable), in which two insulated electric wires extend in parallel and are surrounded by a sheath (protection cover) of a generally oval shape. To extend a branch electric wire from such a VVF cable two connections discussed below are selectively used; (1) a sleeve comprised of a metal tube which is provided, on an inner peripheral surface with a helical groove (see Japanese Utility Kokoku Publication No. 53-3418), and (2) a connector having a connecting element which pierces the insulation of the electric wires which are inserted in respective parallel circular holes, so that the connecting element comes into electrical contact with the electric wires to establish an electrical connection therebetween (see Japanese Patent Kokai Publication No. 51-1992). In the branching operation using the sleeve mentioned above, the VVF cable is cut to remove the sheath and the insulation to expose the electric wire. If the branch conductor is made of a similar VVF cable, the latter is similarly cut to remove the sheath and the insulation. If the branch conductor is a single wire, the insulation thereof is removed to expose the conductor. Thereafter, the exposed conductor portion of the main conductor and the exposed conductor portion of the branch conductor are forced into the sleeve to connect them.
In the branching operation using the connector, the sheath of the VVF cable of the main conductor is removed to produce two portions corresponding to the electric wires. If the branch electric wire is made of the VVF cable, the sheath thereof is removed, and if the branch conductor is made of a single wire, no operation is needed. After that, one of the portions corresponding to the electric wires of the main conductor and the corresponding electrical wire or the portion equivalent thereto of the branch conductor are inserted in the respective holes of the connector. After that the connecting element is mounted to the connector body to pierce the insulation of the electric wires to thereby establish an electrical connection therebetween. Similarly to the foregoing, another connecting element is mounted to the connector body to electrically connect the other portion corresponding to the electrical wire of the main conductor and the corresponding electric wire or the portion equivalent thereto of the branch conductor.
In the connection method utilizing a sleeve, not only is the cutting operation of the VVF cable on the main conductor side necessary, but also operations such as removal of the sheaths and the insulations of both the main conductor and the branch conductor are required. In addition, the conductor portions might be accidentally damaged upon removal of the sheaths and insulation.
In the case where the connector is used, the removal of the sheath of the VVF cable on the main conductor side, and the removal of the VVF cable on the branch conductor side, if the branch conductor is made of the VVF cable, are necessary.
It is, therefore, an object of the present invention to provide a simple and inexpensive connector apparatus in which neither the cutting of the main conductor cable, nor the removal of the sheaths and insulations of the main conductor cable and the branch conductor cable are necessary.